/Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/NonManifoldMappingSupport.h
Return the vertex ID in the potentially non-manifold data used to generate this DynamicMesh associated with the provided vertex id. In the case that the source data was actually manifold the returned vertex id will be identical to the DynamicMesh vertex id.
Note: the code assumes but does not check that vid is a valid vertex vid.
int32 GetOriginalNonManifoldVertexID ( const int32 vid ) const